Secret Sharing And Its Applications

In order to protect data we can encrypt it, but in order to protect the encryption key we need a different method (further encryptions change the problem rather than solve it). The most secure key management scheme keeps the key in a single, well-guarded location (a computer, a human brain, or a safe). This scheme is highly unreliable since a single misfortune (a computer breakdown, sudden death, or sabotage) can make the information inaccessible. An obvious solution is to store multiple copies of the key at different locations, but this increases the danger of security breaches (computer penetration, betrayal, or human errors).Secret sharing can solve the problems mentioned above perfectly. Informally, a secret sharing scheme is a method of distributing a secret key s among a set of participants P in such a way that qualified subsets of P can reconstruct the value of s, whereas any other (non-qualified) subsets of P cannot determine anything about the value of s.Secret sharing schemes are useful in any important action that requires the concurrence of several designated people to be initiated, such as launching a missile, opening a bank vault or even opening a safety deposit box: Secret sharing schemes are also used in management of cryptographic keys and multi-party secure protocols. Secret sharing is an important tool for the information security and the data privacy, and it plays an important role in protecting important information and secret data from being lost, destroyed, viciously modified, or into wrong hands. Secret sharing has been one important branch of modern cryptography and also one important research field of information security. This dissertation reviews the research advances of the secret sharing technology and analysises the design characteristics of most of the existing secret sharing schemes and their restrict and effect on the applications, based on which several secure, efficient and practical secret sharing schemes are designed, the application of secret sharing in digital signature is studied with emphases.A secure and efficient vector space secret sharing-multisignature scheme based on ECC is proposed. The security of this scheme is analyzed. The group signature can be easily produced if an authorized subset of participants pool their secret shares and it is impossible for them to generate a group signature if an unauthorized subset of participants pool their secret shares. The validit}}of the partial signature and the group signature can be verified by means of verification equations. A group signature of an authorized subset of participants cannot be impersonated by any other set of participants. Moreover the suspected forgery and the malicious participants can he found in this scheme. None of several possible attacks can successfully break this scheme.